Allen-Bradley 1784-KTX Reference Manual page 117

Appendix D
Glossary
Module address
Module control byte (MCB)
One slot addressing
Output image table
Programmable interrupt controller
Quad density module
Scanner management request
Standard density module
Two slot addressing
Allen-Bradley Parts
D-2
I/O update
The scanner's serial scan of all I/O chassis in the I/O subsystem.
This scan is asynchronous to scans between the scanner and
host processor.
An address that defines the physical location of the module in the I/O
chassis by its I/O rack number and starting slot number.
The byte entered in the output image table, destined for a block
transfer module, which has one of the two most significant bits set to
indicate a request for a block transfer read or write.
Addressing where an I/O group represents one slot.
An area of memory that controls output switches of output modules.
When a bit is set, its corresponding output is energized. Two hundred
fifty-six 16-bit words (4096 points) are available.
The logic on the PC's motherboard that handles interrupts.
(PIC)
Discrete I/O module having 32 input or output points.
Scan list
A list specifying the order in which I/O adapters are to be scanned.
It is specified by the host and sent to the scanner module as a scanner
management command. Although a maximum of 16 I/O adapters is
allowed, the scan list can specify a maximum of 64 I/O adapters.
This is done to allow the scanner to scan adapters more than once
during its scan cycle if more frequent updates are desired.
A command from the host to the scanner used to control and configure
the scanner board.
Slot
Position in an I/O chassis the width of one discrete I/O module.
Discrete I/O module having 4, 6, or typically 8 input or output points.
Addressing where an I/O group represents two slots.